It definitely could be OT accumulated over the trip. Don't worry - a few days of consistent naps and good nights should help her get over it. She might be going through something developmentally too, yk?
Great to hear about your progress soothing her. They are smart little creatures, huh? Pick up on things so quickly! Another thought I had was that you are getting proper naps with the short A times BUT it might lead to NWs as a result - so something to keep in mind as a culprit for the NWs you're getting. Basically there are a lot of factors in play right now. You just need to slowly work through them. Consistent naps should help with the OT, pushing A will also help lengthen naps and deal with any UT waking.
Regarding 2-1, you can choose to go with either a long am - short pm routine or vice versa. With my DD, am was always the easiest nap and the longest. She naturally started doing a long am nap and so I capped pm to 30 minutes AND pulled BT forward to compensate. Then as A times kept extending (we were doing 5 hours that point) I would either do a quick 10 minute CN with BT at 7pm OR if the nap ended by 2pm, I would go for an EBT of 6pm. I even PD for bed at 5.30 for a while and we got lovely 13-14 hour nights. Basically just made sure that she is getting enough day sleep overall and use EBT to prevent OT. This is a tricky transition.